docs: Work in mention of 1Password shell plugin

What does this MR do?

As noted in https://gitlab.com/gitlab-org/cli/-/issues/7463#note_1765199372 (confidential) we could mention our 1Password integration in the gitlab docs. I created this MR intentionally quite small to open up discussion. We could do more, depending on what @phikai wants to do.

Related issues

• Related to docs: Add mention of 1Password collaboration (cli!1409 - merged) with similar changes in the cli project.

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